Design principles for zero-strain Li-ion cathodes

The cycling of cathode materials for Li-ion batteries is often accompanied by a change in volume, posing a challenge to the integrity of cathode particles and electrolyte/cathode interface in solid-state batteries. To enhance capacity retention, it is thus crucial to design materials that remain structurally invariant during electrochemical cycling. Here, we use well-calibrated first-principles calculations to systematically investigate the effect of transition-metal chemistry, cation ordering, Li site occupancy, redox-inactive species, anion substitution, and cation migration on the volume change associated with the delithiation of cathode materials with an FCC anion framework. Suggested by an in-depth first-principles Monte Carlo simulation of the Li+-V3+-Nb5+-O2--F- system, we experimentally confirm Li1.3V0.4Nb0.3O2 and Li1.25V0.55Nb0.2O1.9F0.1 as nearly zero-strain cathodes. Our study establishes a fundamental understanding of the important physical descriptors that determine the dimensional change of materials during cycling and provides general guidelines for designing low- or zero-strain cathodes.

Automated summary

In this study, the effects of various factors on the volume change during the cycling of cathode materials for Li-ion batteries were systematically investigated using well-calibrated first-principles calculations. The study established a fundamental understanding of the important physical descriptors that determine the dimensional change of materials during cycling and provided general guidelines for designing low- or zero-strain cathodes.